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Choice of long range test loads based on overall group size or vertical group size?

 
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  #8  
Old 08-07-2013, 12:33 PM
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Re: Choice of long range test loads based on overall group size or vertical group siz

If you are in a true accuracy node, a 1/10th grain change in powder charge should make very little difference in accuracy. I am not convinced that your 39.1g load is any more accurate than your 39.0g load. I would argue that both groups fall within a range that your rifle would produce if you continue to fire groups with those loads.

Moreover, at longer distances, I seriously doubt you will be able to hold tight enough to tell the difference between the two (if there is any, and I don't think there is).

I agree that you should shoot your loads at 300 yards and look for vertical. I am betting that neither load shows much vertical. After that, shoot at 600 yards and see what you are getting. But, be advised that shooting at 600 yards is likely to tell you more about your technique and ability to adjust for conditions than it will about your rifle/load combination.
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Old 08-08-2013, 07:47 AM
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Re: Choice of long range test loads based on overall group size or vertical group siz

All those groups are very good. But I don't think there's enough shots in each one for them to be meaningful as far as which load's best. I'd shoot at least 10 shots per group.

I'd ignore the smallest group shot with a given load. Use the largest one. A load's smallest groups happen only when all the variables cancel each other out or everything's perfect; but you cannot tell which it is. The largest groups happen when all the variables add up together and tell you the most you'll miss your point of aim.

If one shoots several groups with the same load and they're not all within 10% of the same size, there's not enough shots in them to be very meaningful as far as what accuracy can be counted on all the time with that load.

Shoot another few-shot group with the same load that produced the smallest one shown in this thread. If it's within 1% of the same size, then it may be the best load to use.

Vertical shot stringing dimensions are often best for load testing at the longer ranges. Especially if there's a variable cross wind. Shooting shoulder fired rifles from a bench with the rifle's fore end resting atop something typically produces greater horizontal shot stringing than when the rifle's fired from prone with a sling properly used and the fore end resting on something.

Last edited by Bart B; 08-08-2013 at 10:32 AM.
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Old 08-08-2013, 09:51 AM
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Re: Choice of long range test loads based on overall group size or vertical group siz

great groups. Take them out to distance and you'll know very quickly
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  #11  
Old 08-14-2013, 01:50 AM
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Re: Choice of long range test loads based on overall group size or vertical group siz

Update:
I loaded some up at 39.0gr and shot an informal 600 yard match.
Load data changed slightly, as I had some issues with neck sizing related in another post I made.
Once fired brass, neck sized in a Wilson neck sizer with a 0.285" bushing, spring back got me 0.286" necks vs the 0.2875" of the new brass. So the neck tension was different. But the other variables stayed the same: COAL 2.800", 130gr bergers, FED205M, 39.0gr of H4350.
We used 300 yard high power slow fire targets at 600.
Shot 2 sighters and 20 record. Shot a 197-5x. The nines were me mucking it up (shot prone off sand bags that weren't great, the Caldwell dead shot bags, with fogging sunglasses as the sun set).
Was still fiddling with the scope a bit through the 20 shots, but once I left it alone, the group settled down and 12 shots were in a group 2" high by 5" wide. I'll have to see next Tuesday how I shoot when I have the gun zeroed and maybe use a better rest system...

PS. I don't have a chronograph or access to one right now...could someone tell me an estimate of my velocity? From a 100 yard zero, it took 14.25MOA to a 600 yard zero. Thanks.
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Old 08-14-2013, 02:35 AM
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Re: Choice of long range test loads based on overall group size or vertical group siz

Go to JBM and plug your information into one of their ballistic calculators. It should give you a ballpark idea of your velocity. From there, you can generate a drop chart and refine it as you shoot.
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  #13  
Old 08-14-2013, 08:15 AM
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Re: Choice of long range test loads based on overall group size or vertical group siz

Quote:
Originally Posted by KiloTango View Post
I loaded some up at 39.0gr and shot an informal 600 yard match.

Was still fiddling with the scope a bit through the 20 shots, but once I left it alone, the group settled down and 12 shots were in a group 2" high by 5" wide. I'll have to see next Tuesday how I shoot when I have the gun zeroed and maybe use a better rest system...

PS. I don't have a chronograph or access to one right now...could someone tell me an estimate of my velocity? From a 100 yard zero, it took 14.25MOA to a 600 yard zero. Thanks.
I think your group's windage spread was caused by wind. But it looks pretty good if only 2" high at 600.

39 grains of H4350 is 6 grains below max i Hodgdon's data showing 45.5 grains shoots a 140 grain bullet out at 2720 fps. Your load may well be close to 2600.

The folks I know winning matches and setting records with the 6.5x.284 in high power matches all full length size their cases and get better accuracy than neck only sizing them. That aside, a 2" x 5" 600 yard group with 12 shots in the wind ain't too shabby. If it can be repeated, then by all means do it.
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  #14  
Old 08-14-2013, 03:11 PM
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Re: Choice of long range test loads based on overall group size or vertical group siz

I ran a pressure ladder test, but was getting odd results from compressed loads, and was seeing that from 40.0gr...I don't think I could fit 45.0gr in a 6.5x47 case and be able to seat a bullet...
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